bpf: hash map: decrement counter on error

Decrement the number of elements in the map in case the allocation
of a new node fails.

Fixes: 6c9059817432 ("bpf: pre-allocate hash map elements")
Signed-off-by: Mauricio Vasquez B <mauricio.vasquez@polito.it>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c
index 3ca2198..513d9df 100644 (file)
--- a/kernel/bpf/hashtab.c
+++ b/kernel/bpf/hashtab.c
@@ -747,13 +747,15 @@ static struct htab_elem *alloc_htab_elem(struct bpf_htab *htab, void *key,
                                 * old element will be freed immediately.
                                 * Otherwise return an error
                                 */
-                               atomic_dec(&htab->count);
-                               return ERR_PTR(-E2BIG);
+                               l_new = ERR_PTR(-E2BIG);
+                               goto dec_count;
                        }
                l_new = kmalloc_node(htab->elem_size, GFP_ATOMIC | __GFP_NOWARN,
                                     htab->map.numa_node);
-               if (!l_new)
-                       return ERR_PTR(-ENOMEM);
+               if (!l_new) {
+                       l_new = ERR_PTR(-ENOMEM);
+                       goto dec_count;
+               }
        }
 
        memcpy(l_new->key, key, key_size);
@@ -766,7 +768,8 @@ static struct htab_elem *alloc_htab_elem(struct bpf_htab *htab, void *key,
                                                  GFP_ATOMIC | __GFP_NOWARN);
                        if (!pptr) {
                                kfree(l_new);
-                               return ERR_PTR(-ENOMEM);
+                               l_new = ERR_PTR(-ENOMEM);
+                               goto dec_count;
                        }
                }
 
@@ -780,6 +783,9 @@ static struct htab_elem *alloc_htab_elem(struct bpf_htab *htab, void *key,
 
        l_new->hash = hash;
        return l_new;
+dec_count:
+       atomic_dec(&htab->count);
+       return l_new;
 }
 
 static int check_flags(struct bpf_htab *htab, struct htab_elem *l_old,